EG91-AUX GSM1800 RSE failure

IoT Modules LTE Standard Module
1

We are seeing an ssue on the spurious emission test on 2G Band for EG91 -AUX

Applicable Standard: EN 301 511
Frequency Band: GSM1800
Test Item: Spurious Emission above 1 GHz
Fail Description:
When the product tested GPRS, the test frequency was 2 times of 1.7476G, the Horizontal polarization exceeded the limit by 2.46 dB ,and the vertical polarization exceeded the limit by 2.03 dB

We have tired disabling the GNSS LNA (including the RF trace to Quectel module) but no improvement.
May I know what other possibility that can cause the harmonics?
For your information, the antenna we used have S11 <-10dB with total efficiency >60%.

2

Hi Peiqii,
1.You need to provide screenshots of GPRS Spurious Emission Test Fail.
2.We need to check the antenna to EG91 module RF Pin schematic and PCB diagram.
3.Remove all antennas from the device, just keep ANT_Main and test again.

Thanks~

3

RSE GSM1800
RSE GSM18001188×636 98.4 KB

please refer attached screenshot of fail result captured…

4

Hi Peiqii,
I recommend reducing the transmission power of the GSM1800 and re-testing it.

image
image602×791 28.8 KB